The present invention relates to a metal laminate gasket having a sealing mechanism around a hole formed of a recess and a flange.
In a metal laminate gasket for an internal combustion engine, the gasket is formed of a plurality of metal plates laminated together. In order to seal around a hole, such as cylinder bores, water holes and oil holes, a portion around the hole to be sealed is made thick or a bead is formed around the hole. Accordingly, when the gasket is tightened, a high surface pressure is formed and concentrated around the hole to thereby seal therearound.
In case a portion around the hole is made thick, a portion of a metal plate for constituting the gasket is turned around the hole, or a grommet is installed around the hole. In this case, the portion around the hole should not be too thick in order not to excessively concentrate surface pressure around the hole. For this purpose, another sheet having a thickness less than that of the turned portion or flange is installed outside the turned portion. Otherwise, the turned portion is made of a very thin metal plate.
Further, an independent annular plate or shim may be installed around the hole to be sealed.
As stated above, in case the turned portion or grommet is used, it is generally necessary to use another plate located outside the turned portion to regulate surface pressure around the turned portion, which must have a thickness slightly less than that of the turned portion. Further, in case the very thin metal plate is used, it is required to prepare the special thin metal plate.
Also, in case a metal plate is turned, the metal plate must have a predetermined thickness to prevent cracking at the time of turning, though the thickness depends on the quality of the plate.
In a conventional metal gasket as stated above, thus, it is necessary to use an extra metal plate for only adjusting the thickness of the gasket. Also, it is very difficult to precisely adjust a surface pressure around the hole to be sealed.
Accordingly, one object of the present invention is to provide a metal laminate gasket, wherein a surface pressure around the hole to be sealed can be easily and precisely determined.
Another object of the invention is to provide a metal laminate gasket as stated above, wherein the portion around the hole can be sealed with a bead without causing creep relaxation of the bead.
A further object of the invention is to provide a metal laminate gasket as stated above, wherein a surface pressure around the hole can be locally adjusted with reference to the distance from the bolt holes.
Further objects and advantages of the invention will be apparent from the following description of the invention.